fix(FN-3789): add @fusion/dashboard to REQUIRED_BUILD_PACKAGES

@fusion/desktop tests dynamically import('@fusion/dashboard') in
local-runtime.ts. When packages/dashboard/dist/index.js is absent
(fresh checkout, merger verification env, CI without an explicit
dashboard build) Vite fails with 'Failed to resolve entry for package
@fusion/dashboard' before the desktop vitest alias takes effect.

scripts/ensure-test-artifacts.mjs is the canonical bootstrap layer
that pnpm test calls before running suites; register @fusion/dashboard
there so the dist is built on demand. Extends node:test coverage
mirroring the hermes/openclaw patterns.

Unblocks: FN-3789, FN-3793, FN-3795, FN-3803 (and any future task
whose merger verification path runs desktop tests).

scripts/ensure-test-artifacts.mjs

@@ -6,6 +6,7 @@ import { spawnSync } from "node:child_process";
 
 export const REQUIRED_BUILD_PACKAGES = [
   { name: "@fusion/core", requiredArtifacts: ["packages/core/dist/index.js"] },
+  { name: "@fusion/dashboard", requiredArtifacts: ["packages/dashboard/dist/index.js"] },
   { name: "@fusion/plugin-sdk", requiredArtifacts: ["packages/plugin-sdk/dist/index.js"] },
   {
     name: "@fusion-plugin-examples/hermes-runtime",